US 2010/0308733 A1 discloses an apparatus and a method for a constant-power offline light-emitting diode driver. A single-stage integrated circuit drives light emitting diode sources in a constant power mode to eliminate the need for light emitting diode current sensing, while re-shaping the waveform of the inductor current near line zero crossing to achieve a high power factor.
From FIG. 6 of US 2010/0308733 A1 it can be derived that the apparatus and the method suffer from a relatively low distortion power factor. Such a relatively low distortion power factor corresponds to relatively much distortion.